From:	Zach Heilig <heilig AT cs DOT und DOT nodak DOT edu>
Subject:	Re: NULL pointers in (ANSI) string functions [was: strcat() ?]
To:	sandmann AT new-orleans DOT NeoSoft DOT com (Charles Sandmann)
Date:	Tue, 1 Nov 1994 20:53:47 -0600 (CST)
Cc:	djgpp AT sun DOT soe DOT clarkson DOT edu

Charles Sandmann says:
> DPMI does not currently have null pointer protection, so under DPMI you
> would currently just use whatever happens to be in page 0 of the memory
> block.  Under V1.11 page 0 was never written, so your dpmi provider 
> probably had it all zeros.  Due to a minor bug in the V1.12 LD, the
> protection page wasn't being generated so the memory at location 0 was
> being written with the COFF header (I think).  I can't be sure this is true, 
> but because of the LD problem I don't think any (early?) V1.12 images
> provide null pointer protection at all.
> 
> Anyway, it will all get fixed someday, and work under DPMI too.

Probably the easiest fix would be to change the NULL pointer to
something way out of range, like maybe: 0xffffffff.  It may break some
code to have it != 0x00000000, but that code was really broken anyway,
since a NULL pointer is definately not guaranteed to be 0x00000000
after translation is done.  I don't know if there is an easy way to
make gcc translate a 0 in a pointer context to the real NULL pointer,
though.

-- 
	Zach Heilig	(heilig AT aero DOT und DOT nodak DOT edu)

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